Programming Perl

Lorrie Faith Cranor


The first thing you notice about the Perl book is the camel. The hardy beast is standing nonchalantly and grinning ever so slyly. This is not just any old desert dwelling dromedary. This is a camel with an attitude. And that's the way Perl creator and Programming Perl co-author Larry Wall wanted it to be. Wall likens the camel-with-an-attitude to his free Practical Extraction and Report Language -- Perl. ``It's ugly but useful,'' he says. Since 1986 when Wall first developed Perl -- an interpreted data reduction language -- to solve a problem that awk could not handle, the language has grown to include a variety of built-in functions, associative arrays, regular expression handling, object-oriented features, and some of the most useful bits of several other programming languages. It is now a popular tool for system administrators and programmers who want to develop code to manipulate strings, files, and processes. Recently it has become the language of choice for programming interactive applications on the World Wide Web. As Wall has developed and improved Perl, utility has always been a higher priority than theoretical elegance. He criticizes other modern languages that have been developed by people who ``try to define their languages such that you can't do anything bad.'' As a result, he says, ``the act of programming becomes joyless.'' But, not so with Perl. ``The thing that people really like about Perl is that they have fun.'' This is perhaps why Perl has become so popular. With the help of volunteers from around the world, Wall put the finishing touches on Perl version 5 in mid-October. Perl 5 introduces not only new features -- including simple object oriented ideas and a more readable syntax -- but also a new philosophy. Wall explains that as Perl developed, new features were continuously added, causing the language to change constantly. ``With Perl 5 I've sort of come to the realization that we need to actually stabilize the language itself and provide an official way of extending it.'' Therefore, Perl 5 includes mechanisms that allow programmers to add reusable modules to extend the Perl language. The object-oriented features were necessary to add this extensibility. In addition, they allow Perl and C++ to be easily used within the same program. As with versions 1 through 4, the new features of version 5 have been designed so that they can be learned incrementally.